Semiconductor device and manufacturing method thereof

ABSTRACT

A semiconductor device comprises a fin structure disposed over a substrate; a gate structure disposed over part of the fin structure; a source/drain structure, which includes part of the fin structure not covered by the gate structure; an interlayer dielectric layer formed over the fin structure, the gate structure, and the source/drain structure; a contact hole formed in the interlayer dielectric layer; and a contact material disposed in the contact hole. The fin structure extends in a first direction and includes an upper layer, wherein a part of the upper layer is exposed from an isolation insulating layer. The gate structure extends in a second direction perpendicular to the first direction. The contact material includes a silicon phosphide layer and a metal layer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Divisional Application of U.S. application Ser.No. 16/459,529, filed Jul. 1, 2019, which is a Divisional Application ofU.S. application Ser. No. 15/653,094, filed Jul. 18, 2017, now U.S. Pat.No. 10,340,366, which is a Divisional Application of U.S. applicationSer. No. 14/714,227, filed May 15, 2015, now U.S. Pat. No. 9,741,829,the entire disclosure of each of which are incorporated herein byreference.

TECHNICAL FIELD

The disclosure relates to a semiconductor integrated circuit, moreparticularly to a semiconductor device having a metal gate structure andits manufacturing process.

BACKGROUND

As the semiconductor industry has progressed into nanometer technologyprocess nodes in pursuit of higher device density, higher performance,and lower costs, challenges from both fabrication and design issues haveresulted in the development of three-dimensional designs, such as a finfield effect transistor (Fin FET) and the use of a metal gate structurewith a high-k (dielectric constant) material. The metal gate structureis often manufactured by using gate replacement technologies, andsources and drains are formed in a recessed fin by using an epitaxialgrowth method. Further, germanium (Ge) or a Ge compound is also used asa base material instead of silicon for its higher electron mobility.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detaileddescription when read with the accompanying figures. It is emphasizedthat, in accordance with the standard practice in the industry, variousfeatures are not drawn to scale and are used for illustration purposesonly. In fact, the dimensions of the various features may be arbitrarilyincreased or reduced for clarity of discussion.

FIG. 1 is an exemplary plan view of a Ge Fin FET device according to oneembodiment of the present disclosure.

FIG. 2 is an exemplary flow chart for manufacturing a Ge Fin FET deviceaccording to a first embodiment of the present disclosure.

FIGS. 3A-11B show exemplary views of various stages for manufacturing aGe Fin FET device according to the first embodiment of the presentdisclosure.

FIG. 12 is an exemplary flow chart for manufacturing a Ge Fin FET deviceaccording to a modified first embodiment of the present disclosure.

FIGS. 13A-14B show exemplary views of various stages for manufacturing aGe Fin FET device according to the modified first embodiment of thepresent disclosure.

FIG. 15 is an exemplary flow chart for manufacturing a Ge Fin FET deviceaccording to a second embodiment of the present disclosure.

FIGS. 16A-22B show exemplary views of various stages for manufacturing aGe Fin FET device according to the second embodiment of the presentdisclosure.

FIG. 23 is an exemplary flow chart for manufacturing a Ge Fin FET deviceaccording to a modified second embodiment of the present disclosure.

FIGS. 24A-25B show exemplary views of various stages for manufacturing aGe Fin FET device according to the modified second embodiment of thepresent disclosure.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides manydifferent embodiments, or examples, for implementing different featuresof the invention. Specific embodiments or examples of components andarrangements are described below to simplify the present disclosure.These are, of course, merely examples and are not intended to belimiting. For example, dimensions of elements are not limited to thedisclosed range or values, but may depend upon process conditions and/ordesired properties of the device. Moreover, the formation of a firstfeature over or on a second feature in the description that follows mayinclude embodiments in which the first and second features are formed indirect contact, and may also include embodiments in which additionalfeatures may be formed interposing the first and second features, suchthat the first and second features may not be in direct contact. Variousfeatures may be arbitrarily drawn in different scales for simplicity andclarity.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly. In addition, the term“made of” may mean either “comprising” or “consisting of.”

FIG. 1 is an exemplary plan view of a Ge Fin FET device according to oneembodiment of the present disclosure. In one embodiment, the Ge Fin FETis an N-type FET.

In one embodiment of the present disclosure, multiple fin structures 20are disposed over a substrate 10 and multiple gate electrodes 100 aredisposed over the fin structures 20, as shown in FIG. 1. In someembodiments, one or more dummy gate electrodes 100D are also disposed atboth sides of the gate electrodes 100 over the substrate 10. Similarly,one or more dummy fin structures may be disposed at both sides of thefin structures 20. Although in FIG. 1, the dummy gate electrodes 100Dare not disposed over any part of fin structures, the dummy gateelectrodes 100D may be disposed over part of the fin structures 20 insome embodiments. As shown in FIG. 1, four fin structures 20 extend inthe X direction and three gate electrodes 100 and two dummy gateelectrodes 100D extend in the Y direction. However, the number of finsstructures and/or gate electrodes is not limited.

As shown in FIG. 1, the Fin FET device also includes a source 120 and adrain 130. As set forth below, due to an epitaxial growth of asource/drain material, the width of the source and drain in plan view iswider than the width of the fin structure. The Fin FET device furtherincludes a source contact 125 and a drain contact 135.

FIG. 2 is an exemplary flow chart for manufacturing a Ge Fin FET deviceaccording to a first embodiment of the present disclosure. The flowchart illustrates only a relevant part of the entire manufacturingprocess for a Ge Fin FET device. It is understood that additionaloperations may be provided before, during, and after the operationsshown by FIG. 2, and some of the operations described below can bereplaced or eliminated for additional embodiments of the method. Theorder of the operations/processes may be interchangeable.

The following embodiments mainly describe a Ge Fin FET device as oneexample of the semiconductor device and the manufacturing methodthereof, and the technologies described herein are also applicable tohorizontal multi-gate transistors, stacked nanowire transistors and/ortri-gate transistors.

FIGS. 3A and 3B are exemplary cross sectional views a Ge Fin FET deviceat one of the various stages of the fabrication process according to thefirst embodiment of the present disclosure. FIG. 3A corresponds to across sectional view along the line X-X′ of FIG. 1 and FIG. 3Bcorresponds to a cross sectional view along the line Y-Y′ of FIG. 1.

In S101 of FIG. 2, dummy gate structures are formed over a substrate 10.Fin structures 20 are fabricated over the substrate, and protrude froman isolation insulating layer 50. The portions of the fin structures 20protruding from the isolation insulating layer 50 function as channellayers.

To fabricate fin structures according to one embodiment, a mask layer isformed over a substrate. The mask layer is formed by, for example, athermal oxidation process and/or a chemical vapor deposition (CVD)process. The substrate 10 is, for example, a p-type silicon or germaniumsubstrate with an impurity concentration in a range of about 1×10¹⁵ cm⁻³to about 1×10¹⁶ cm⁻³. In other embodiments, the substrate is an n-typesilicon or germanium substrate with an impurity concentration in a rangeof about 1×10¹⁵ cm⁻³ to about 1×10¹⁶ cm⁻³. The mask layer includes, forexample, a pad oxide (e.g., silicon oxide) layer and a silicon nitridemask layer in some embodiments. The substrate 10 may also be aSi_(x)Ge_(1-x) substrate, where x=0.1 to 0.9 (hereinafter referred to asSiGe). The germanium substrate may include a germanium layer or a SiGelayer formed over another substrate such as a silicon substrate.Further, the germanium substrate may include a germanium layer or a SiGelayer formed over an oxide layer (e.g., SiGe oxide) that is disposedover another substrate. The substrate may include various regions thathave been suitably doped with impurities (e.g., p-type or n-typeconductivity).

The pad oxide layer may be formed by using thermal oxidation or a CVDprocess. The silicon nitride mask layer may be formed by a physicalvapor deposition (PVD), such as a sputtering method, a CVD,plasma-enhanced chemical vapor deposition (PECVD), an atmosphericpressure chemical vapor deposition (APCVD), a low-pressure CVD (LPCVD),a high density plasma CVD (HDPCVD), an atomic layer deposition (ALD),and/or other processes.

The thickness of the pad oxide layer is in a range of about 2 nm toabout 15 nm and the thickness of the silicon nitride mask layer is in arange of about 2 nm to about 50 nm in some embodiments. A mask patternis further formed over the mask layer. The mask pattern is, for example,a resist pattern formed by lithography operations.

By using the mask pattern as an etching mask, a hard mask pattern of thepad oxide layer and the silicon nitride mask layer is formed. The widthof the hard mask pattern is in a range of about 5 nm to about 40 nm insome embodiments. In certain embodiments, the width of the hard maskpatterns is in a range of about 7 nm to about 12 nm.

By using the hard mask pattern as an etching mask, the substrate ispatterned into fin structures 20 by trench etching using a dry etchingmethod and/or a wet etching method. A height of the fin structures 20 isin a range of about 20 nm to about 300 nm. In certain embodiments, theheight is in a range of about 30 nm to about 60 nm. When the heights ofthe fin structures are not uniform, the height from the substrate may bemeasured from the plane that corresponds to the average heights of thefin structures. The width of the fin structures 20 is in a range ofabout 4 nm to about 15 nm.

When multiple fin structures are disposed, the space between the finstructures is in a range of about 5 nm to about 80 nm in someembodiments, and may be in a range of about 7 nm to about 15 nm in otherembodiments. One skilled in the art will realize, however, that thedimensions and values recited throughout the descriptions are merelyexamples, and may be changed to suit different scales of integratedcircuits.

After forming the fin structures 20, an isolation insulating layer 50 isformed over the fin structures 20. The isolation insulating layer 50includes one or more layers of insulating materials such as siliconoxide, silicon oxynitride or silicon nitride, formed by LPCVD (lowpressure chemical vapor deposition), plasma-CVD or flowable CVD. In theflowable CVD, flowable dielectric materials instead of silicon oxide maybe deposited. Flowable dielectric materials, as their name suggest, can“flow” during deposition to fill gaps or spaces with a high aspectratio. Usually, various chemistries are added to silicon-containingprecursors to allow the deposited film to flow. In some embodiments,nitrogen hydride bonds are added. Examples of flowable dielectricprecursors, particularly flowable silicon oxide precursors, include asilicate, a siloxane, a methyl silsesquioxane (MSQ), a hydrogensilsesquioxane (HSQ), an MSQ/HSQ, a perhydrosilazane (TCPS), aperhydro-polysilazane (PSZ), a tetraethyl orthosilicate (TEOS), or asilyl-amine, such as trisilylamine (TSA). These flowable silicon oxidematerials are formed in a multiple-operation process. After the flowablefilm is deposited, it is cured and then annealed to remove un-desiredelement(s) to form silicon oxide. When the un-desired element(s) isremoved, the flowable film densifies and shrinks. In some embodiments,multiple anneal processes are conducted. The flowable film is cured andannealed more than once. The flowable film may be doped with boronand/or phosphorous. The isolation insulating layer 50 may be formed byone or more layers of SOG, SiO, SiON, SiOCN and/or fluoride-dopedsilicate glass (FSG) in some embodiments.

After forming the isolation insulating layer 50 over the fin structures20, a planarization operation is performed so as to remove part of theisolation insulating layer 50 and the mask layer (the pad oxide layerand the silicon nitride mask layer). The planarization operation mayinclude a chemical mechanical polishing (CMP) and/or an etch-backprocess. Then, the isolation insulating layer 50 is further removed sothat the channel layer (upper layer) of the fin structures 20 isexposed. The height of the channel layer (upper layer) is in a rage ofabout 20 nm to about 60 nm.

In certain embodiments, the partially removing the isolation insulatinglayer 50 may be performed using a wet etching process, for example, bydipping the substrate in hydrofluoric acid (HF). In another embodiment,the partially removing the isolation insulating layer 50 may beperformed using a dry etching process. For example, a dry etchingprocess using CHF₃ or BF₃ as etching gases may be used.

After forming the isolation insulating layer 50, a thermal process, forexample, an anneal process, may be performed to improve the quality ofthe isolation insulating layer 50. In certain embodiments, the thermalprocess is performed by using rapid thermal annealing (RTA) at atemperature in a range of about 900° C. to about 1050° C. for about 1.5seconds to about 10 seconds in an inert gas ambient, such as an N₂, Aror He ambient.

A dielectric layer and a poly silicon layer are formed over theisolation insulating layer 50 and the exposed fin structure, and thenpatterning operations are performed so as to obtain a dummy gatestructure including dummy gate layers 210, 210D made of poly silicon anda dummy gate dielectric layer (not shown). The patterning of the polysilicon layer is performed by using a hard mask 200, 200D including asilicon nitride layer formed over a silicon oxide layer in someembodiments. In other embodiments, the hard mask may include a siliconoxide layer formed over a silicon nitride layer. The dummy gatedielectric layer may be silicon oxide formed by CVD, PVD, ALD, e-beamevaporation, or other suitable process. In some embodiments, the gatedielectric layer may include one or more layers of silicon oxide,silicon nitride, silicon oxy-nitride, or high-k dielectrics. In someembodiments, a thickness of the gate dielectric layer is in a range ofabout 2 nm to about 20 nm, and in a range of about 2 nm to about 10 nmin other embodiments.

In some embodiments, the dummy gate layers 210, 210D may comprise asingle layer or multilayer structure. The dummy gate layers 210, 201Dmay be doped poly silicon with uniform or non-uniform doping. The dummygate layers 210, 210D may be formed using a suitable process such asALD, CVD, PVD, or combinations thereof. In the present embodiment, thewidth of the dummy gate layers 210, 210D is in the range of about 30 nmto about 60 nm. In some embodiments, a thickness of the gate electrodelayer is in a range of about 50 nm to about 400 nm, and may be in arange of about 100 nm to 200 nm.

Further, insulating spacer (side-wall spacer) layers are formed over thedummy gate structure. The insulating spacers may include silicon oxidelayers 220, 220D and silicon nitride layers 225, 225D in someembodiments. As shown in FIG. 3A, three dummy gate electrodes layers 210corresponding to gate electrodes 100 are disposed over the finstructures 20 (and the isolation insulating layer 50), and two dummygate layers 210D corresponding to the dummy gate electrodes 100D are notdisposed over the fin structures. A shown in FIG. 3B, part of the finstructures not covered by dummy gate layers become source and drainregions.

In S102 of FIG. 2, recesses 230 are formed in part of the fin structuresnot covered by dummy gate layers. FIGS. 4A and 4B are exemplary crosssectional views of the Ge Fin FET device at one of the various stages ofthe fabrication process according to the first embodiment of the presentdisclosure. FIG. 4A corresponds to a cross sectional view along the lineX-X′ of FIG. 1 and FIG. 4B corresponds to a cross sectional view alongthe line Y-Y′ of FIG. 1. The depth of the recesses 230 is in a range ofabout 20 nm to about 60 nm in some embodiments.

The recess etching of the fin structures 20 is performed by plasmaetching using gases including CH₄, CF₄, CH₂F₂, CHF₃, O₂, HBr, Cl₂, NF₃,N₂ and/or He under a pressure of 3 to 20 mTorr, in some embodiments. Therecess etching is anisotropic etching.

In S103 of FIG. 2, a source/drain (S/D) epitaxial layer 240 is formed inpart of the fin structures not covered by dummy gate layers, as shown inFIGS. 5A and 5B. FIGS. 5A and 5B are exemplary cross sectional views ofthe Ge Fin FET device at one of the various stages of the fabricationprocess according to the first embodiment of the present disclosure.FIG. 5A corresponds to a cross sectional view along the line X-X′ ofFIG. 1 and FIG. 5B corresponds to a cross sectional view along the lineY-Y′ of FIG. 1.

The S/D epitaxial layer 240 includes GeP (germanium phosphide) in someembodiments. A concentration of P may be in a range of about 1×10²⁰ toabout 2×10²⁰ cm⁻³. When the main surface of the substrate is a (100)surface, the S/D epitaxial layer grows vertically and laterally, andforms a “diamond” shape in the cross section, as shown in FIG. 5B. TheGeP epitaxial grown is performed at a temperature of about 600 to 800°C. under a pressure of about 80 to 150 Torr, by using a Ge containinggas such as GeH₄, Ge₂H₆, GeCl₂H₂ and a phosphorous containing gas suchas PH₃. With this epitaxial growth, the GeP layers are selectivelyformed in and over the recesses 230 of the fin structures.

In S104 of FIG. 2, a first interlayer dielectric layer is formed overthe resulting structure of FIGS. 5A and 5B, and planarization operationsare performed. The resultant structure after the planarizationoperations are shown in FIGS. 6A and 6B. FIGS. 6A and 6B are exemplarycross sectional views of the Ge Fin FET device at one of the variousstages of the fabrication process according to the first embodiment ofthe present disclosure. FIG. 6A corresponds to a cross sectional viewalong the line X-X′ of FIG. 1 and FIG. 6B corresponds to a crosssectional view along the line Y-Y′ of FIG. 1.

In some embodiments, the first interlayer dielectric layer may include afirst dielectric layer 250 and a second dielectric layer 260. The firstdielectric layer 250 may be made of silicon nitride and function as acontact-etch-stop layer. The second dielectric layer 260 may include oneor more layers of silicon oxide, silicon nitride, silicon oxynitride(SiON), SiOCN, fluoride-doped silicate glass (FSG), or a low-Kdielectric material, formed by CVD. In other embodiments, the firstinterlayer dielectric layer may be a single layer.

The planarization operations are performed to remove part of the firstinterlayer dielectric layer. The planarization operations include achemical mechanical polishing (CMP) and/or an etch-back process. By thisplanarization operation, hard masks 200, 200D are also removed.

In S105 of FIG. 2, metal gate structures are formed, as shown in FIGS.7A and 7B. FIGS. 7A and 7B are exemplary cross sectional views of the GeFin FET device at one of the various stages of the fabrication processaccording to the first embodiment of the present disclosure. FIG. 7Acorresponds to a cross sectional view along the line X-X′ of FIG. 1 andFIG. 7B corresponds to a cross sectional view along the line Y-Y′ ofFIG. 1.

The dummy gate layers 210, 210D and the dummy dielectric layer areremoved, by appropriate etching processes, respectively, to formopenings. Metal gate structures including a gate dielectric layer (notshown) and metal gate layers 270, 270D are formed in the openings, asshown in FIGS. 7A and 7B.

The gate dielectric layer may be formed over an interface layer (notshown) disposed over the channel layer of the fin structures 20. Theinterface layer may include silicon oxide or germanium oxide with athickness of 0.2 nm to 1.5 nm in some embodiments. The germanium oxideinterface layer may be formed by oxidizing the Ge channel layer. Inother embodiments, the thickness of the interface layer is in a rangeabout 0.5 nm to about 1.0 nm.

The gate dielectric layer includes one or more layers of dielectricmaterials, such as silicon oxide, silicon nitride, or high-k dielectricmaterial, other suitable dielectric material, and/or combinationsthereof. Examples of high-k dielectric material include HfO₂, HfSiO,HfSiON, HfTaO, HfTiO, HfZrO, zirconium oxide, aluminum oxide, titaniumoxide, hafnium dioxide-alumina (HfO₂—Al₂O₃) alloy, other suitable high-kdielectric materials, and/or combinations thereof. The gate dielectriclayer is formed by, for example, chemical vapor deposition (CVD),physical vapor deposition (PVD), atomic layer deposition (ALD), highdensity plasma CVD (HDPCVD), or other suitable methods, and/orcombinations thereof. The thickness of the gate dielectric layer is in arange of about 1 nm to about 10 nm in some embodiments, and may be in arange of about 2 nm to about 7 nm in other embodiments. In someembodiments, the gate dielectric layer 30 may include an interfaciallayer made of silicon dioxide.

Metal gate electrodes 270, 270D are formed over the gate dielectriclayer. The metal gate electrodes 270, 270D include any suitable metalmaterial, such as aluminum, copper, titanium, tantalum, cobalt,molybdenum, tantalum nitride, nickel silicide, cobalt silicide, TiN, WN,TiAl, TiAlN, TaCN, TaC, TaSiN, metal alloys, other suitable materials,and/or combinations thereof.

In certain embodiments of the present disclosure, one or more workfunction adjustment layers (not shown) may be interposed between thegate dielectric layer and the metal gate electrodes 270, 270D. The workfunction adjustment layers are made of a conductive material such as asingle layer of TiN, TaN, TaAlC, TiC, TaC, Co, Al, TiAl, HfTi, TiSi,TaSi or TiAlC, or a multilayer of two or more of these materials. Forthe n-channel Fin FET, one or more of TaN, TaAlC, TiN, TiC, Co, TiAl,HfTi, TiSi and TaSi is used as the work function adjustment layer, andfor the p-channel Fin FET, one or more of TiAlC, Al, TiAl, TaN, TaAlC,TiN, TiC and Co is used as the work function adjustment layer.

After depositing appropriate materials for the metal gate structures,planarization operations such as a CMP are performed, thereby obtainingthe structure shown in FIGS. 7A and 7B.

In S106 of FIG. 2, a second interlayer dielectric layer is formed overthe resultant structure shown in FIGS. 7A and 7B, and contact holes 300are formed as shown in FIGS. 8A and 8B. FIGS. 8A and 8B are exemplarycross sectional views of the Ge Fin FET device at one of the variousstages of the fabrication process according to the first embodiment ofthe present disclosure. FIG. 8A corresponds to a cross sectional viewalong the line X-X′ of FIG. 1 and FIG. 8B corresponds to a crosssectional view along the line Y-Y′ of FIG. 1.

In some embodiments, the second interlayer dielectric layer may includea first insulating layer 280 and a second insulating layer 290. Thefirst insulating layer 280 may be made of silicon nitride and functionas a contact-etch-stop layer. The second insulating layer 290 mayinclude silicon oxide, silicon nitride, silicon oxynitride (SiON),SiOCN, fluoride-doped silicate glass (FSG), or a low-K dielectricmaterial, formed by CVD. In other embodiments, the second interlayerdielectric layer may be a single layer.

By using a patterning operation including lithography, contact holes 300are formed in the second and first interlayer dielectric layers 280,290, so as to expose source and drain regions.

In S107 of FIG. 2, a cap layer 310 is formed in the contact holes asshown in FIGS. 9A and 9B. FIGS. 9A and 9B are exemplary cross sectionalviews of the Ge Fin FET device at one of the various stages of thefabrication process according to the first embodiment of the presentdisclosure. FIG. 9A corresponds to a cross sectional view along the lineX-X′ of FIG. 1 and FIG. 9B corresponds to a cross sectional view alongthe line Y-Y′ of FIG. 1.

The cap layer 310 may include SiP (silicon phosphide). A concentrationof P in the cap layer may be in a range of about 1×10²¹ to about 3×10²¹cm⁻³. The SiP formation is performed at a low temperature of about 300to 600° C. under a pressure of about 20 to 60 Torr, by using a Sicontaining gas such as SiH₄, Si₂H₆, SiCl₂H₂ and a phosphorous containinggas such as PH₃. By this deposition, SiP is formed not only on thesource/drain regions of the fin structures but also on the interlayerdielectric layers and the sidewalls of the contact holes 300. Thethickness of the SiP layer 310 is in a range of about 8 nm to about 10nm on the source/drain regions and in a range of about 4 nm to about 6nm on the interlayer dielectric layers and the sidewalls of the contactholes 300. The SiP layer 310 may be epitaxially grown over thesource/drain regions of the fin structures.

In S108 of FIG. 2, a contact metal layer 320 is formed over the caplayer 310 as shown in FIGS. 10A and 10B. FIGS. 10A and 10B are exemplarycross sectional views of the Ge Fin FET device at one of the variousstages of the fabrication process according to the first embodiment ofthe present disclosure. FIG. 10A corresponds to a cross sectional viewalong the line X-X′ of FIG. 1 and FIG. 10B corresponds to a crosssectional view along the line Y-Y′ of FIG. 1.

The contact metal layer 320 may include a single layer or multiplelayers of any suitable metal such as Co, W, Ti, Ta, Cu, Al and/or Niand/or nitride thereof. After forming the contact metal layer 320, analloy layer may be formed between the cap layer 310 and contact metallayer 320. For example, a silicide formation operation may be performedso as to make a silicide layer 325 between the contact metal layer 320and SiP cap layer 310. The silicide formation operations may include anannealing process at a temperature of about 250° C. to 850° C.

The thickness of the silicide layer 325 on the source/drain regions isin a range of about 5 nm to about 7 nm, and a portion of the SiP layerremains after silicide formation.

In S109 of FIG. 2, planarization operations are performed to remove partof the metal layer 320, silicide layer 325 and cap layer 310, and theresultant structure shown in FIGS. 11A and 11B is obtained. FIGS. 11Aand 11B are exemplary cross sectional views of the Ge Fin FET device atone of the various stages of the fabrication process according to thefirst embodiment of the present disclosure. FIG. 11A corresponds to across sectional view along the line X-X′ of FIG. 1 and FIG. 11Bcorresponds to a cross sectional view along the line Y-Y′ of FIG. 1.

The planarization operations may include a CMP and/or an etch-backprocess. Part of the metal layer 320, silicide layer 325 and cap layer310 disposed over the second interlayer dielectric layer are removed.

After the planarization operations, further CMOS processes are performedto form various features such as additional interlayer dielectric layer,contacts/vias, interconnect metal layers, and passivation layers, etc.

FIG. 12 is an exemplary flow chart for manufacturing a Ge Fin FET deviceaccording to a modified first embodiment of the present disclosure. InFIG. 12, S101-S109 are substantially the same as FIG. 2. In the modifiedfirst embodiment, a thin high-k dielectric layer 410 is formed (S111)between the SiP cap layer (S107) and the metal contact layer (S108).

FIGS. 13A and 13B are exemplary cross sectional views of the Ge Fin FETdevice at one of the various stages of the fabrication process accordingto the modified first embodiment of the present disclosure. FIG. 13Acorresponds to a cross sectional view along the line X-X′ of FIG. 1 andFIG. 13B corresponds to a cross sectional view along the line Y-Y′ ofFIG. 1.

In S107 of FIG. 12, similar to S107 of FIG. 1, a SiP cap layer isformed. In the modified first embodiment, however, the thickness of SiPlayer 310 is in a range of about 4 nm to about 6 nm on the source/drainregions and in a range of about 1 nm to about 2 nm on the interlayerdielectric layers and the sidewalls of the contact holes 300.

In S111 of FIG. 12, a thin high-k dielectric layer 410 is formed overthe SiP cap layer 310. The thickness of the dielectric layer 410 is in arange of about 0.5 nm to about 3 nm. The high-k dielectric layer 410 mayinclude silicon nitrides, aluminum oxides, aluminum oxide/siliconoxides, lanthanum oxides and/or lanthanum oxide/silicon oxides when thecap layer is silicon base. The high-k dielectric layer may includegermanium nitrides, silicon oxynitrides, germanium oxides, aluminumoxides, magnesium oxides, and/or titanium oxides when the cap layer isgermanium based. These dielectric materials may be stoichiometic ornon-stoichiometric oxides compositions.

After forming the high-k dielectric layer 410, operations S108 and S109of FIG. 12, which are substantially the same as S108 and S109 of FIG. 2,are performed, thereby obtaining the structure shown in FIGS. 14A and14B. FIG. 14A corresponds to a cross sectional view along the line X-X′of FIG. 1 and FIG. 14B corresponds to a cross sectional view along theline Y-Y′ of FIG. 1.

Although a dielectric layer 410 is disposed between the SiP cap layer310 and the metal contact layer 320, because of a high dielectricconstant and a small thickness, the tunnel barrier height in a bandstructure (MIS diagram) is reduced and a lower contact resistance can beobtained.

FIG. 15 is an exemplary flow chart for manufacturing a Ge Fin FET deviceaccording to a second embodiment of the present disclosure. The flowchart illustrates only a relevant part of the entire manufacturingprocess for a Ge Fin FET device. It is understood that additionaloperations may be provided before, during, and after processes shown byFIG. 15, and some of the operations described below can be replaced oreliminated for additional embodiments of the method. The order of theoperations/processes may be interchangeable. The same or similaroperations, processes, and materials as the first embodiment may be usedin the second embodiment.

Similar to S101 of the first embodiment, dummy gate structures areformed in S201 of FIG. 15. The resultant structure is the same as FIGS.3A and 3B. After the dummy gate structures are formed, a firstinterlayer dielectric layer including a first dielectric layer 250 and asecond dielectric layer 260 are formed in S202 of FIG. 15. Planarizationoperations, such as CMP, are performed to remove part of the firstinterlayer dielectric layer. The resultant structure is shown in FIGS.16A and 16B. FIG. 16A corresponds to a cross sectional view along theline X-X′ of FIG. 1 and FIG. 16B corresponds to a cross sectional viewalong the line Y-Y′ of FIG. 1. Unlike FIGS. 6A and 6B of the firstembodiment, recesses and S/D epitaxial layers are not formed.

Similar to S105 of the first embodiment, metal gate structures areformed in S203. The dummy gate layers 210, 210D and the dummy dielectriclayer are removed, by appropriate etching processes, respectively, toform openings. Metal gate structures including a gate dielectric layer(not shown) and metal gate layers 270, 270D are formed in the openings,as shown in FIGS. 17A and 17B. FIG. 17A corresponds to a cross sectionalview along the line X-X′ of FIG. 1 and FIG. 17B corresponds to a crosssectional view along the line Y-Y′ of FIG. 1.

Similar to S106 of the first embodiment, a second interlayer dielectriclayer including a first insulating layer 280 and a second insulatinglayer 290 is formed, and contact holes 300 are formed in the second andfirst interlayer dielectric layers, so as to expose source and drainregions, in S204 of FIG. 15. The resultant structure is shown in FIGS.18A and 18B. FIG. 18A corresponds to a cross sectional view along theline X-X′ of FIG. 1 and FIG. 18B corresponds to a cross sectional viewalong the line Y-Y′ of FIG. 1.

In S205 of FIG. 15, a source/drain (S/D) epitaxial layer 510, 510′ isformed. Similar to S102 of the first embodiment, recesses are formed inpart of the fin structures exposed in the contact holes 300. Similar toS102 of the first embodiment, an S/D epitaxial layer 510 is formed inthe recess over the fin structures, as shown in FIGS. 19A and 19B. FIG.19A corresponds to a cross sectional view along the line X-X′ of FIG. 1and FIG. 19B corresponds to a cross sectional view along the line Y-Y′of FIG. 1.

The S/D epitaxial layer 510, 510′ includes GeP (germanium phosphide) insome embodiments. A concentration of P may be in a range of about 2×10²⁰to about 6×10²⁰ cm⁻³, which is higher than the P concentration of theGeP layer 240 of the first embodiment. The GeP epitaxial grown isperformed at a temperature of about 300 to 600° C. under a pressure ofabout 80 to 150 Torr, by using a Ge containing gas such as GeH₄, Ge₂H₆,GeCl₂H₂ and a phosphorous containing gas such as PH₃. With thisepitaxial growth, the GeP layers are formed not only on the finstructures, but also on the isolation insulating layer 50, the sidewalls of the contact holes 300 and the second interlayer dielectriclayer, as shown in FIGS. 19A and 19B. The thickness of the GeP layer510′ formed on the isolation insulating layer 50, the side walls of thecontact holes 300 and the second interlayer dielectric layer is in arange of about 1 nm to about 2 nm.

In S206 of FIG. 15, a cap layer 520 is formed in the contact holes asshown in FIGS. 20A and 20B, similar to S107 of the first embodiment.FIGS. 20A and 20B are exemplary cross sectional views of the Ge Fin FETdevice at one of the various stages of the fabrication process accordingto the first embodiment of the present disclosure. FIG. 20A correspondsto a cross sectional view along the line X-X′ of FIG. 1 and FIG. 20Bcorresponds to a cross sectional view along the line Y-Y′ of FIG. 1.

The cap layer 520 may include SiP (silicon phosphide). A concentrationof P may be in a range of about 1×10²¹ to about 3×10²¹ cm⁻³. The SiPformation is performed at a low temperature of about 300 to 600° C.under a pressure of about 20 to 60 Torr, by using a Si containing gassuch as SiH₄, Si₂H₆, SiCl₂H₂ and a phosphorous containing gas such asPH₃. By this deposition, SiP is formed not only on the source/drainregions (GeP layer 510) of the fin structures but also on the GeP layer510′ formed on the interlayer dielectric layers and the sidewalls of thecontact holes 300. The thickness of SiP layer 520 is in a range of about8 nm to about 10 nm on the source/drain regions and in a range of about4 nm to about 6 nm over the interlayer dielectric layers and thesidewalls of the contact holes 300. The SiP layer 520 may be epitaxiallygrown over the source/drain regions of the fin structures.

In S207 of FIG. 15, similar to S108 of the first embodiment, a contactmetal layer 320 is formed over the cap layer 520 as shown in FIGS. 21Aand 21B. FIGS. 21A and 21B are exemplary cross sectional views of the GeFin FET device at one of the various stages of the fabrication processaccording to the first embodiment of the present disclosure. FIG. 21Acorresponds to a cross sectional view along the line X-X′ of FIG. 1 andFIG. 21B corresponds to a cross sectional view along the line Y-Y′ ofFIG. 1.

After forming the contact metal layer 320, an alloy layer may be formedbetween the cap layer 520 and contact metal layer 320. For example, asilicide formation operation may be performed so as to make a silicidelayer 525 between the contact metal layer 320 and SiP cap layer 520. Thesilicide formation operations may include an annealing process at atemperature of about 250° C. to 850° C.

The thickness of the silicide layer 525 on the source/drain regions isin a range of about 5 nm to about 7 nm, and a portion of the SiP layerremains after silicidation.

In S208 of FIG. 15, similar to S109 of the first embodiment,planarization operations are performed to remove part of the metal layer320, silicide layer 525 and cap layer 520, and the resultant structureshown in FIGS. 22A and 22B is obtained. FIGS. 22A and 22B are exemplarycross sectional views of the Ge Fin FET device at one of the variousstages of the fabrication process according to the first embodiment ofthe present disclosure. FIG. 22A corresponds to a cross sectional viewalong the line X-X′ of FIG. 1 and FIG. 22B corresponds to a crosssectional view along the line Y-Y′ of FIG. 1.

The planarization operations may include a CMP and/or an etch-backprocess. Part of the metal layer 320, silicide layer 525 and cap layer520 disposed over the second interlayer dielectric layer are removed.

After the planarization operations, further CMOS processes are performedto form various features such as additional interlayer dielectric layer,contacts/vias, interconnect metal layers, and passivation layers, etc.

FIG. 23 is an exemplary flow chart for manufacturing a Ge Fin FET deviceaccording to a modified second embodiment of the present disclosure. InFIG. 23, S201-S208 are substantially the same as FIG. 12. In themodified second embodiment, a thin high-k dielectric layer 610 is formed(S211) between the SiP cap layer (S206) and the metal contact layer(S207).

FIGS. 24A and 24B are exemplary cross sectional views of the Ge Fin FETdevice at one of the various stages of the fabrication process accordingto the modified second embodiment of the present disclosure. FIG. 24Acorresponds to a cross sectional view along the line X-X′ of FIG. 1 andFIG. 24B corresponds to a cross sectional view along the line Y-Y′ ofFIG. 1.

In S206 of FIG. 23, similar to S206 of FIG. 15, a SiP cap layer isformed. In the modified second embodiment, however, the thickness of SiPlayer 520 is in a range of about 4 nm to about 6 nm on the source/drainregions and in a range of about 1 nm to about 2 nm on the interlayerdielectric layers and the sidewalls of the contact holes 300.

In S211 of FIG. 23, a thin high-k dielectric layer 610 is formed overthe SiP cap layer 520. The thickness of the dielectric layer 610 is in arange of about 0.5 nm to about 3 nm. The high-k dielectric layer 610 mayinclude silicon nitrides, aluminum oxides, aluminum oxide/siliconoxides, lanthanum oxides, and/or lanthanum oxide/silicon oxides when thecap layer is silicon based. The high-k dielectric layer may includegermanium nitrides, silicon oxynitrides, germanium oxides, aluminumoxides, magnesium oxides, and/or titanium oxides when the cap layer isgermanium based. These dielectric materials may be stoichiometic ornon-stoichiometric compositions.

After forming the high-k dielectric layer 610, operations S207 and S208of FIG. 15 are performed, thereby obtaining the structure shown in FIGS.25A and 25B. FIG. 25A corresponds to a cross sectional view along theline X-X′ of FIG. 1 and FIG. 25B corresponds to a cross sectional viewalong the line Y-Y′ of FIG. 1.

Although a dielectric layer 620 is disposed between the SiP cap layer520 and the metal contact layer 320, because of a high dielectricconstant and a small thickness, the tunnel barrier height in a bandstructure (MIS diagram) is reduced and a lower contact resistance can beobtained.

In the first and second embodiments, a gate-replacement technology witha metal gate electrode and a high-k gate dielectric is employed.However, a gate-first technology with a poly-gate structure may also beemployed. In the gate-first technology, the dummy gate layers 210 arethe gate electrodes.

Generally, the use of Ge or a Ge based material has problems such as alower N-type dopant activation level and Fermi level pinning near thevalence band, which cause an increase of an N-type contact resistancebetween source/drains and contact metals for N-type Ge Fin FETs. In thepresent disclosure, by using N⁺ SiP cap layer formed over thesource/drain GeP layer, the Fermi level pinning can be suppressed.

Further, the SiP cap layer is formed after the contact hole formation,it is possible to prevent the cap layer from missing in the contactetching process. Further, an N-type contact resistance betweensource/drain and contact metals for N-type Ge Fin FETs can be reduced.

It will be understood that not all advantages have been necessarilydiscussed herein, no particular advantage is required for allembodiments or examples, and other embodiments or examples may offerdifferent advantages.

In accordance with one aspect of the present disclosure, in a method ofmanufacturing a semiconductor device including a Fin FET, a finstructure is formed over a substrate. The fin structure extends in afirst direction and includes an upper layer. Part of the upper layer isexposed from an isolation insulating layer. A source/drain structure isformed in the fin structure. A gate structure is formed over part of thefin structure. The gate structure extends in a second directionperpendicular to the first direction. An interlayer dielectric layer isformed over the fin structure, the source/drain structure and the gatestructure. A contact hole is formed in the interlayer dielectric layerso that the source/drain structure is exposed. A cap layer is formed inthe contact hole. A contact metal layer is formed over the cap layer.

In accordance with another aspect of the present disclosure, in a methodof manufacturing a semiconductor device including a Fin FET, a finstructure is formed over a substrate. The fin structure extends in afirst direction and includes an upper layer. Part of the upper layer isexposed from an isolation insulating layer. A gate structure is formedover part of the fin structure. The gate structure extends in a seconddirection perpendicular to the first direction. An amorphous layer isformed over the gate structure and the fin structure not covered by thegate structure. An interlayer dielectric layer is formed over the finstructure and the gate structure. A contact hole is formed in theinterlayer dielectric layer so that part of the fin structure isexposed. A source/drain structure is formed in the exposed finstructure. A cap layer is formed in the contact hole over thesource/drain structure. A contact metal layer is formed over the caplayer.

In accordance with another aspect of the present disclosure, asemiconductor device includes a fin structure disposed over a substrate;a gate structure disposed over part of the fin structure; a source/drainstructure, which includes part of the fin structure not covered by thegate structure; an interlayer dielectric layer formed over the finstructure, the gate structure, and the source/drain structure; a contacthole formed in the interlayer dielectric layer; and a contact materialdisposed in the contact hole. The fin structure extends in a firstdirection and includes an upper layer, wherein a part of the upper layerbeing exposed from an isolation insulating layer. The gate structureextends in a second direction perpendicular to the first direction. Thecontact material includes a silicon phosphide layer and a metal layer.

The foregoing outlines features of several embodiments or examples sothat those skilled in the art may better understand the aspects of thepresent disclosure. Those skilled in the art should appreciate that theymay readily use the present disclosure as a basis for designing ormodifying other processes and structures for carrying out the samepurposes and/or achieving the same advantages of the embodiments orexamples introduced herein. Those skilled in the art should also realizethat such equivalent constructions do not depart from the spirit andscope of the present disclosure, and that they may make various changes,substitutions, and alterations herein without departing from the spiritand scope of the present disclosure.

What is claimed is:
 1. A semiconductor device comprising: a finstructure disposed over a substrate, the fin structure extending in afirst direction and including an upper layer, part of the upper layerbeing exposed from an isolation insulating layer; a gate structuredisposed over part of the fin structure, the gate structure extending ina second direction perpendicular to the first direction; a source/drainstructure which includes part of the fin structure not covered by thegate structure; an interlayer dielectric layer formed over the finstructure, the gate structure and the source/drain structure; a contacthole formed in the interlayer dielectric layer exposing the source/drainstructure; and a contact material, wherein: the contact materialincludes a silicon phosphide layer and a metal layer disposed over thesilicon phosphide layer, and the silicon phosphide layer covers thesource/drain structure, an upper surface of the isolation insulatinglayer, and sidewalls of the interlayer dielectric layer, wherein theupper surface of the isolation insulating layer is opposed to a surfacefacing the substrate.
 2. The semiconductor device of claim 1, furthercomprising an alloy layer between the silicon phosphide layer and themetal layer.
 3. The semiconductor device of claim 2, wherein the alloylayer is a silicide.
 4. The semiconductor device of claim 1, wherein thefin structure is made of germanium or a germanium compound.
 5. Thesemiconductor device of claim 1, wherein the source/drain structureincludes germanium phosphide.
 6. The semiconductor device of claim 1,wherein the metal layer comprises a single layer or multiple layersincluding Co, W, Ti, Ta, Cu, Al, or Ni.
 7. The semiconductor device ofclaim 1, wherein the interlayer dielectric layer includes a firstdielectric layer and a second dielectric layer.
 8. The semiconductordevice of claim 7, wherein the first dielectric layer is an etch stoplayer.
 9. A semiconductor device comprising: a fin structure disposedover a substrate, wherein the fin structure extends in a first directionand includes an upper layer, part of the upper layer is exposed from anisolation insulating layer, the isolation insulating layer has a firstsurface and an opposing second surface, and the first surface faces thesubstrate; a gate structure disposed over part of the fin structure, thegate structure extending in a second direction perpendicular to thefirst direction; a source/drain structure which includes a first portionpart of the fin structure not covered by the gate structure; aninterlayer dielectric layer formed over a second portion of the finstructure; and a cap layer disposed over the source/drain structure, thesecond surface of the isolation insulating layer and sidewalls of theinterlayer dielectric layer.
 10. The semiconductor device of claim 9,wherein the cap layer includes silicon phosphide.
 11. The semiconductordevice of claim 9, wherein the fin structure is made of germanium or agermanium compound.
 12. The semiconductor device of claim 9, wherein thesource/drain structure includes germanium phosphide.
 13. Thesemiconductor device of claim 9, further comprising a silicide layerdisposed over the cap layer.
 14. The semiconductor device of claim 13,further comprising a metal layer disposed over the silicide layer.
 15. Asemiconductor device comprising: a plurality of fin structures disposedover a substrate, each of the fin structures extends in a firstdirection; an isolation insulating layer disposed between adjacent finstructures, wherein the isolation insulating layer has a first surfaceand an opposing second surface, and the first surface faces thesubstrate; a plurality of source/drain structures disposed over andprotruding from parts of the fin structures not covered by the gatestructures; an interlayer dielectric layer formed over each of the finstructures outside the plurality of fin structures; an epitaxial layerdisposed over the interlayer dielectric layer and the second surface ofthe isolation insulating layer; and a cap layer disposed over theepitaxial layer and each of the source/drain structures.
 16. Thesemiconductor device of claim 15, wherein the cap layer includes siliconphosphide.
 17. The semiconductor device of claim 15, wherein the finstructure is made of germanium or a germanium compound.
 18. Thesemiconductor device of claim 15, wherein the source/drain structureincludes germanium phosphide.
 19. The semiconductor device of claim 15,further comprising a metal layer disposed over the cap layer, whereinthe metal layer comprises a single layer or multiple layers includingCo, W, Ti, Ta, Cu, Al, or Ni.
 20. The semiconductor device of claim 15,wherein the interlayer dielectric layer includes a first dielectriclayer and a second dielectric layer.